1. Field of the Invention
This invention generally relates to a device for removing ozone in a predetermined space, and in particular to an ozone removing device suitable for use in such apparatuses as electrophototraphic copiers, laser printers and facsimile machines.
2. Description of the Prior Art
In various image forming apparatuses using an electrophotographic process, such as copiers, laser printers and facsimile machines, use is typically made of a corona discharge unit for emitting corona ions as a charging unit for charging a photosensitive member uniformly and also as an image transfer unit for transferring a toner image from the photosensitive member to a sheet of plain paper. Thus, ozone is also produced mainly by such corona discharge units and thus the image forming apparatus becomes often filled with ozone after a relatively long period of operation. Since ozone would deteriorate the performance of the photosensitive member, it is preferable to remove the ozone produced within the housing of an image forming apparatus. For this purpose, an ozone removing device is often used in an image forming apparatus.
A typical prior art ozone removing device includes activated carbon or a metal oxide as an ozone decomposing agent. Such a prior art ozone decomposing agent is a solid material and it removes ozone by absorption. Thus, the prior art ozone decomposing agent becomes effective in removing ozone from the air once the ozone to be removed comes into contact with the ozone decomposing agent by drifting. In order to provide an enhanced rate of removal of ozone, it is required to dispose an ozone removing device as close as possible to a location where ozone is generated or to dispose an ozone removing device at a ventilation exit through which ozone is discharged. Another problem with the prior art ozone removing device is its relatively large size, which tends to inhibit to make the overall size of an image forming apparatus smaller.
In an image forming apparatus in which the provision of such an ozone removing device is desired, limited space makes it difficult to dispose an ozone removing device in the vicinity of an ozone-generating location. Besides, to dispose an ozone removing device at a ventilation exit would tend to increase the pressure drop, interfering with adequate ventilation inside of an imaging machine and causing an undesirable temperature rise inside of an image forming apparatus. In addition, the prior art ozone decomposing agent of activated carbon or a metal oxide is initially effective in removing ozone; however, its ozone removing capability radically drops due to aging. Thus, if it is desired to prolong the service life of the prior art ozone removing device, it is necessary to increase the amount of ozone decomposing agent to be used in an ozone removing device, which would again tend to make the entire device bulky in structure and high at cost.